Die casting machines



March 14, 1961 A. R. MILLS 2,974,379

DIE CASTING MACHINES Filed July 26, 1957 5 ZA/ Men/7214:

United States Patent 2,974,379- DIE CASTING MACHINES Aubrey RobertMills, London, England, assignor to Die Casting Machine Tools Limited,London, England, a British company Filed July 26, 1957, Ser. No. 674,501

Claims priority, application Great Britain July 27, 1956 1 Claim. (Cl.22-67) This invention relates to die casting machines of the kind,hereinafter referred to as the kind described, having two dies which arebrought together to form a mould into which the casting material isinjected and are then moved apart -for the casting to be ejected.

According to this invention, in a die casting machine of the kinddescribed, means are provided for brushing the dies after they have beenmoved apart. Most conveniently, said means are actuated automaticallyby, or in timed relation with, the die moving means. For example, amicro-switch may be arranged tobe operated by the die moving means or bya part connected thereto,

which micro'switch controls an electrical circuit for initiating theoperation of means for moving the brush over the die, which means maycomprise an air-operated piston and cylinder assembly.

The brushing of the dies serves to keep them clean and preferably isetfected by a wire brush or brushes. Such brush or brushes may bearranged not only to clean the faces of the dies but also, if necessary,to lubricate the dies and/or to put graphite solution on the dies as issometimes required when new dies are taken into service. It will beappreciated that in die casting machines, it is the common practice tohave one stationary die and one moving die and to have one or moreejector pins passing through the moving die plate and extending in thedirection of movement thereof, which pins are held stationary when thedies are moved apart so that the pins force the casting from the movingdie. Such ejector pins require periodical lubrication and, particularlyin die casting machines operating automatically for the repetitiveproduction of castings, regular lubrication is necessary and isconveniently eflected by brushing in the man ner described above.

The aforementioned means for brushing the dies conveniently comprise twobrushes arranged back-toback and suitably shaped so as to brush thesurface of the two dies respectively. It will be understood that thebrushes would have to pass between or around the ejector pins, and/orany cores which may be required in the mould.

vThe brushes themselves will, in general, ensure positive ejection ofthe casting but a suitable projection or the like may be provided on thebrushes or on the brush operating means for this purpose.

In the following description reference will be made to the accompanyingdrawing in which Figure 1 is a perspective view of part of a die castingmachine; and

Figure 2 is a scrap end view of a brush and part of the brush operatingmechanism.

Referring to the drawings, there is shown a fixed die plate and amovable die plate 1 2 which can be closed together to form a mould. Thefixed die plate 10 is mounted on a platen 12 through which molten metalfrom a suitably heated bath 13 can be injected into the mould by meansof a plunger (not shown) operated by a compressed air piston andcylinder assembly 14. The

"i1 ce movable die plate .=1 1 is slidable on tour guide bars 15arranged at the :four corners of the die plates and is moved by means ofa toggle linkage 16, this toggle linkage conveniently being operated byanother compressed air piston and cylinder assembly (not shown).

The apparatus thus far described may be of known construction. Thepresent invention is concerned more particularly with the provision ofmeans for brushing the die plates and -for this purpose there isprovided a pair of brushes 20, 21 mounted back to back on a brush holder22 which brush holder is mounted on the piston of a further compressedair piston and cylinder assembly 23. The piston and cylinder assembly 23is carried on a plate 24 supported on the horizontal part of an L-shapedmember 25, the upright portion of which is bolted to the aforementionedplaten 1'2. The L-shaped member 25 preferably has vertical slots throughwhich pass the bolts for bolting the member to the platen 12 arranged sothat the member 25 and hence the brush operating cylinder 23 may beraised or lowered as required to accommodate the provision of differentsized die plates in the machine. Furthermore the plate 24, as shown hasslots 26 for bolts 27 by which it is bolted to the horizontal part ofthe member 23 so that the plate 24 may be adjusted in position in thedirection of movement of the movable die plate 12 thereby permitting ofadjustment of the position of the brushes 20, 21 for die plates ofvarying thickness. To prevent any twisting of the piston and brushassembly about the cylinder axis, there is secured to the brush holder22 a rod 28 (Figure 2) extending parallel to the axis of the cylinder 23and passing through a bush in the plate 24. To control the op eration ofthe cylinder 23, there is provided a microswitch 30 operated by themovable die plate .11 or part attached thereto or moving in synchronismtherewith and this switch is shown in Figure 1 as being positioned so asto be operated by the movable die plate 11 when the latter reaches theposition of maximum opening of the die plates. This switch 30, by meansof an electrical connection 31, controls a solenoid-operated changeovervalve 32 for reversing the connections of the air supply 33 to the endsof the cylinder 23 and so causes the brushes 20, 21 to be moveddownwardly between the two die plates 10, 12. A further switch 34,operated by a projection 35 on the aforementioned guide rod 28 isprovided for returning the reversing valve 32 to its normal positionwhen the brushes 20, 21 have reached the lower limit of their travel.

Lubricating means indicated diagrammatically by a pipe 36 are providedfor spraying a lubricant, such as a graphite solution, onto the brush 21and a similar lubricating device (not shown) is provided tor lubricatingthe brush 20. These lubricating means may conveniently be operated bythe compressed air from the cylinder 23 but other ways of applyinglubricant to the brushes will be obvious to those skilled in the art.The lubricant applied to the brushes is spread by the brushes over thedie plates and, in particular, over any ejector pins or cores such asthe core 37 and the ejector pins of which the rear ends are shown at 38.

The brush and brush holder serve the further important advantage thatthey ensure positive ejection of a casting from a mould. This is ofparticular importance in an automatic machine and, in such a machine,preferably the brush-operating mechanism is interlocked with the dieplate operating mechanism to ensure that the die plates cannot be closedtogether until the brushes have made a full stroke across the dies andback again. In a compressed-air operated machine, the interlocking maybe the air valves.

I claim:

A die casting machine comprising in combination, a pair of dies havingsubstantially parallel vertical surfaces and movable horizontally towardeach other, to form a mold, and away from each other for removal of acasting; a brush holder supported on said machine above said dies forsubstantially vertical linear reciprocation between the separated dies;a pair of brushes mounted on said holder in back to back relation andeach projecting toward the surface of one of said dies for conjointcleaning of both die surfaces by reciprocation of said brush holder; atfluid pressure actuator connected to said brush holder for poweroperation of the latter; control means for said actuator, including acontrol element in the path of retracting movement of one die operable,when ac- 15 2,054,476

tuated, to condition said control means to energize said actuator tomove said brush holder downwardly between said die surfaces; and asecond control element operable by said actuator at the limit of suchdownward movement to condition said control means to energize saidactuator to move said brush holder upward-1y; said machine includinginterlocking means preventing closure of said dies before said brushholder is retracted.

References Cited in the file of this patent UNITED STATES PATENTS BensonOct. 27, 1868 Korsmo Nov. 23, 1926 Derry et al Sept. 15, 1936

